FIG. 1 depicts a typical suspended ceiling system of the torsion spring type according to the Background art. System 1 includes a plurality of ceiling panels 2 that are supported by a grid 4. Torsion springs 12 hold each panel 2 against a foot portion 4a of the grid 4. One of the panels 2, namely panel 2a, is depicted as being in the open or partially disconnected position. Two of the torsion springs 12, namely torsion springs 12a, are shown in the disengaged position relative to butterfly clips 6. The other two torsion springs 12 of panel 2a are disconnected from their corresponding butterfly clips (not shown).
The dangling ceiling panel 2a shows that each panel 2 has a metal frame 8 around its circumferential edge. Clips 10 permit the frame 8 to be connected to a torsional spring 12.
FIG. 2 shows the relationships between the support grid 4 and the ceiling panels 2 in more detail. In FIG. 2, the support grid is formed of known T-bars 250. Each T-bar 250 has a foot flange 253, a web 251 and a bead portion 254. Attached to the bead 254 is a butterfly clip 230 via a releasable fastener, e.g., a screw 240. Each butterfly clip 230 includes a U-shaped channel 232 and a projecting flange 234 into which is formed a slot 236. Arms 218 of the torsional spring 214 fit into ends of the slot 236. The torsional spring 214 is shown in the disengaged position wherein retaining feet 220 of the torsional spring 214 rest against an upper surface of the projecting flange 234.
A framed panel 20 has a frame 26 formed around the circumferential edge of the panel 28. The framed panel 20 can have an optional fabric cover 210. An attachment clip 212 fits over a flange of the frame 2b. A hook portion of an attachment clip 212 fits into the wound portion 216 of the torsional spring 214.
To fit the framed panel 20 against the T-bars 250, the arms 218 of the torsion spring 14 are pushed up through the slot 236 resulting in the arms 218 spreading out in a v-shape. Consequently, the frame 26 (or the fabric 210) will bear against the foot portion 253 of the T-bar. To assist in aligning adjacent panels, an optional alignment clip 290 can be attached to the T-bar 250.
Panels are typically two feet by two feet. But, some systems feature larger panels, e.g., four feet by eight feet (a standard size in the construction industry). Such a large-panel system is depicted in FIGS. 3. Each of the panels 32 in the system 30 is substantially planar. Unfortunately, one of the panels, namely panel 34, has begun to sag. This can create a very negative impression for a viewer, e.g., as if the system is of poor quality and/or the building is poorly maintained.
Also, panels 32 typically have a nominal (N) thickness plus a tolerance (T), effectively resulting in a size range from a minimum size (Min), where Min=N−T, to a maximum size (Max), where Max=N+T. Where the tolerance is not very small, the effect is to produce a grid system 1 that does not give the impression of forming a planar surface as the ceiling.
The non-planar surface problem is illustrated more particularly in FIG. 4, where such a system 40 with significant panel tolerances is depicted. For the purposes of illustration, the system 40 is very simplified. Panels 46A represent nominal thickness panels. Panel 46B represents a minimum thickness panel. And panel 46C represents a maximum thickness panel. Back surfaces 48 of each panel bear against foot portions 44 of T-bars 42 via force of torsion spring arrangements (not shown, again for simplicity). The varying thicknesses of the panels 46A, 46B and 46C result in the faces 49a, 49b and 49c, respectively, being different distances from the foot portions 44. And that gives the viewer of such a system 40 the impression that the ceiling is non-planar.